Peroxide removal from drug delivery vehicle

ABSTRACT

The present invention is related to methods for lowering peroxide levels in sucrose acetate isobutyrate formulations and to composition used in and formed by such methods.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional application No.60/702,546, filed Jul. 26, 2005, which is incorporated herein in itsentirety.

FIELD OF THE INVENTION

The present invention relates to methods for reducing peroxide levels innon-polymeric preparations and to compositions used in and prepared bysuch methods.

BACKGROUND OF THE INVENTION

Sucrose acetate isobutyrate (“SAIB”) is a hydrophobic liquid withlimited water solubility. It is soluble in a large number ofbiocompatible solvents. SAIB has an unusual property—it undergoes adramatic change in viscosity with small additions of heat or with theaddition of solvents. It is a very viscous liquid, having a viscosity ofapproximately 3200 poise at 37° C. SAID is produced by the controlledesterification of natural sugar (sucrose) with acetic and isobutyricanhydrides. SAID metabolizes to sucrose, acetic acid and isobutyricacid.

SAIB is orally non-toxic and is currently used to stabilize emulsions inthe food industry. In one example, SAID is commonly found in thebeverage industry, where it is used as a weighting agent to helpstabilize the final beverage formula. Also, SAIB has been reported to beuseful as a gelling system-type drug excipient that allows for sustainedor controlled release of drugs. When in solution or in an emulsion, SAIBcan be applied via injection or an aerosol spray. SAID is compatiblewith cellulose esters and other polymers that can affect the rate ofdelivery of the substance. In one example, SAIB is the main ingredientfor the SABER drug delivery system, which also consists of apharmaceutically acceptable solvent.

Drug delivery systems, including SAIB delivery systems, are stillconfronted by various issues of drug instability, as such systems areconsidered for longer and longer drug delivery durations. Druginstability can occur via a number of factors, including denaturation,precipitation, oxidation, aggregation, and others. In particular, anumber of excipients used to facilitate delivery and release of drugshave peroxides or are susceptible to the formation of peroxides, whichmay lead to oxidation of active ingredient in the formulation. In theexample of SAIB, the presence of peroxides is deleterious to a drugincorporated in an SAID drug formulation as the drug is likely toundergo oxidative degradation. Thus, in order to formulate any drugformulation based on SAID that provides enough of a stable environmentto facilitate the delivery of a drug, the peroxide levels must bereduced.

There is no known process for removal of peroxides from SAIB at present,despite availability of processes for the removal of peroxides fromother materials such as polymers. Therefore, there still remains a needfor a drug formulation of SAIB having improved properties to reduce thedegradation of the drug therein.

SUMMARY OF THE INVENTION

An aspect of the present invention comprises methods of treating sucroseacetate isobutyrate (SAIB) formulations to be used as drug deliveryvehicles comprising adding to the formulations an amount of bisulfitesalt effective to substantially remove peroxides, the bisulfite saltcomprising sodium metabisulfite, potassium metabisulfite, sodiumbisulfite, or potassium bisulfite, or a mixture thereof.

In another aspect of the present invention, provided ae drug deliveryvehicles adapted to provide prolonged stability of a drug that is to bedelivered in vivo comprising sucrose acetate isobutyrate havingsubstantially reduced levels of peroxide, the drug delivery vehiclebeing treated with an amount of bisulfite salt effective tosubstantially reduce levels of peroxide in said drug delivery vehicle,the bisulfite salt comprising sodium metabisulfite, potassiummetabisulfite, sodium bisulfite, or potassium bisulfite, or acombination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated by way of example and is not intended to belimited by the accompanying figures.

FIG. 1 illustrates a bar graph of the results of Study I—Stability ofomega-interferon in untreated SAIB.

FIG. 2 illustrates a bar graph of the results of Study IIa—Stability ofomega-interferon in alumina treated SAIB.

FIG. 3 illustrates a bar graph of the results of Study IIb—Stability ofomega-interferon in alumina treated SAID.

FIG. 4 illustrates a bar graph of the results of Study III—Stability ofomega-interferon in untreated SAID.

FIG. 5 illustrates a bar graph of the results of Study VIb—Stability ofomega-interferon in untreated SAIB.

FIG. 6 illustrates a bar graph of the results of Study VIa—Stability ofomega-interferon in sodium metabisulfite treated SAIB.

FIG. 7 illustrates a bar graph that provides comparisons of oxidation ofomega-IFN in sodium metabisulfite treated and untreated SAID.

FIG. 8 illustrates an osmotically pump-driven implantable device, Duros®being an example, that facilitates in vivo delivery of an active agentin an SAIB vehicle.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

In an aspect of the present invention, provided are methods of treatingsucrose acetate isobutyrate formulations (SAIB) that are to be used asdrug delivery vehicles comprising adding an amount of a bisulfite salteffective for substantially removing peroxide from the formulations, thebisulfite salt comprising sodium metabisulfite, potassium metabisulfite,sodium bisulfite, or potassium bisulfite, or a combination thereof.Preferably, the bisulfite salt is sodium metabisulfite. A ratio rangingfrom about 1:1 to about 1:4 (weight:volume) SAIB:aqueous solution ofbisulfite salt (“aqueous bisulfite salt”) can be used. Preferably, thebisulfite salt is a metabisulfite salt. In some embodiments, thebisulfite salt is preferably sodium metabisulfite. Preferably, the ratioof the aqueous bisulfite salt to SAID is 1:1. In one example, to purify1 kg of SAI, a volume of sodium metabisulfite solution can be made up to1 liter, and an approximate proportion of 1:1 of SAIB:aqueous sodiummetabisulfite was used. The aqueous bisulfite salt in SAIB can be fromabout 0.1% weight to volume of water (w/v) to about 50% w/v; preferably,from about 0.5% w/v to about 30% w/v. In some embodiments, the aqueousbisulfite salt is preferably from about 1% w/v to about 15% w/v. In someembodiments, the aqueous bisulfite salt is about 5% w/v solution inwater.

The method removes peroxide to a level that is at east less than 50% ofthe levels before the method, or starting levels, and, preferably, lessthan 20% of the starting levels. In some embodiments, peroxide isremoved to less than 10% of the starting levels. While in someembodiments, the method removes peroxide to a level that is less than 5%of the starting levels. Furthermore, the method can remove peroxide sothat the resulting SAIB formulation contains peroxide in amounts lessthan 20 ppm, and, preferably, less than 10 ppm. In some embodiments, themethod removes peroxide to result in an SAIB formulation containing lessthan 5 ppm. In some embodiments, the resulting SAI formulation from thismethod can serve as a drug delivery vehicle for use with a medicaldelivery device, including a drug eluting stent, a catheter, or otherdrug delivery implants. In one example, the SAIB formulation can beloaded into an osmotically pump-driven implantable device of the typedisclosed in U.S. Pat. No. 6,395,292, for example. Preferably, theosmotically pump-driven implantable device is a Duros® device (AlzaCorporation, Mountain View, Calif.). In other embodiments, the SAIBformulation can serve as a drug depot for-drug delivery.

In some embodiments, the step of adding the bisulfite salt comprisesmixing a solution of the bisulfite salt with the sucrose acetateisobutyrate formulation. The SAIB formulation can be further comprisedof a cosolvent, which can be selected from a number of solventsincluding pharmaceutically acceptable solvents, e.g., hexane, ethylacetate, ethanol, benzyl benzoate, N-methyl pyrrolidone, and iso-propylalcohol, among others. Preferably, the cosolvent is hexane or ethylacetate. In some embodiments, the methods further comprise vacuumtreating the formulation to remove the cosolvent. Also, some embodimentscomprise the additional step of removing bisulfite salt from theformulation. This removal step comprises washing the formulation withwater to remove the bisulfite salt. In the embodiments that incorporatethe washing step, a further step of drying the formulation overmagnesium sulfate can be utilized to remove the water. Alternatively,calcium chloride anhydrous, calcium sulfate anhydrous, activated silicagel, phosphorous pentoxide, or drying under vacuum, or a combinationthereof can be used to also remove the water. In alternativeembodiments, glycerin can be used to wash the bisulfite-addedformulation to remove the bisulfite salt. Afterwards, residual glycerincan be removed by washing with water and then drying to remove water.

In some aspects of the present invention, the methods of substantiallyremoving peroxide from a sucrose acetate isobutyrate formulation (SAIB)comprising the steps of adding the aqueous bisulfite salt, washing theformulation, and drying the formulation am repeated at least once. Thesteps can be repeated to further reduce the levels of peroxide in theSAIB formulation.

In another aspect, the present invention includes a drug deliveryvehicle comprising SAIB that provides for prolonged stability of a drugthat is to be delivered by maintaining substantially reduced levels ofperoxide, the drug delivery vehicle being treated with sodiummetabisulfite. The prolonged stability comprises reduced oxidation,deamidation, or aggregation, e.g., dimerization, of the drug overextended periods of time in which drug is within environment of deliveryvehicle. Preferably the prolonged stability is reduced oxidation. Theextended periods of time can be periods from about one week to a fewmonths, and up to about a year. Preferably, the prolonged stability isevidenced by significant improvements in oxidation, deamidation, oraggregation levels of the drug when the delivery vehicle has beentreated with a bisulfite salt versus untreated delivery vehicle. In somepreferred embodiments, the prolonged stability is characterized as about50% less oxidation, about 33% less deamidation, or about 75% lessdimerization as compared to untreated delivery vehicles. The drug can beselected from any known and desired biomolecular material that can actas therapeutics and other therapeutic active agents that are susceptibleto oxidative degradation. As it is used herein, the term “biomolecularmaterial” refers to peptides, polypeptides, proteins, nucleic acids,viruses, antibodies, small molecules susceptible to oxidation, and anyother naturally derived, synthetically produced, or recombinantlyproduced active agent that includes nucleic or amino acid. In someembodiments, for example, drugs can be selected from among thefollowing: a steroid, NSAIDS, peptides, proteins such as growth factorsor hormones, anti-tumor agents, antibiotics, analgesics, localanesthetics, antiviral agents, antipsychotics, anticoagulants,oligonucleotides for gene therapy, active small molecules, and others.

As used herein, the term “removing” and all variations thereof, refer todecreasing by any measurable degree the level of peroxide present in adrug formulation. The term “substantially removing” is used herein todescribe a dramatic decrease in the level of peroxide present in a drugformulation, such as SAIB formulation. The dramatic decrease is at least50% of original levels (levels before treatment) and in some instancesis 10% of original levels. In preferred aspects of the presentinvention, the “substantial removal” describes a decrease to less than5% of original levels.

As used herein, the term “drug delivery vehicle” or “delivery vehicle”refers to a formulation that is biocompatible and used to carry a drugwithout reacting with the same drug. Also, the vehicle does not alter orminimally alters the activity of the drug. Furthermore, the vehicleallows for the transport of the drug in vivo and eventual delivery ofthe drug to a biological site for therapeutic effect.

As used herein, the term “prolonged stability” is used to refer to thestabilizing effect of the drug delivery vehicles of the presentinvention on the carried drug. Prolonged stability can be evidenced bysignificant improvements in oxidation, deamidation, or aggregation ofthe drug over extended periods of time.

EXAMPLES

Different approaches were investigated for removal of peroxides fromSAIB, as indicated in Table 1.

Preparation of Suspension

Each of the experiments involved protein particles consisting ofomega-interferon, which were suspended in SAIB at a particle loading ofeither 4% or 10% by weight. The suspensions were prepared in a dry boxunder nitrogen at 45° C. The suspension was mixed for 15 minutes whilemaintaining the temperature. Suspension mixing was performed by hand.Aliquots from the prepared suspensions were transferred to clearcrimp-top glass vials and sealed under nitrogen. Each aliquot containedat least six milligrams of protein to allow for stability testing intriplicate. These samples were stored in an oven at 40° C. Samples werewithdrawn at regular intervals (as indicated in Table 1) and analyzedfor omega-interferon content and purity was assessed using reverse phaseHPLC and size exclusion chromatography.

Size Exclusion Chromatography

Size exclusion chromatography (SEC) was used to monitor theomega-interferon content and purity in the formulations. The percentagesof monomer and dimer in the formulation were quantified using SEC. Thestability of omega-interferon was judged by using a stability indicatingchromatographic technique based on reverse phase HPLC (rp-HPLC). Thistechnique was used to monitor the oxidation, deamidation and formationof an unknown species of omega-interferon in the formulations. Theperoxide content of the vehicle was determined using EP 2002, 2.5.5(Method A with auto titration). See Extra Pharmacopoeia, 2002 Ed.Content and purity assay of omega-interferon by size exclusionchromatography (SEC).

Reverse Phase High Performance Liquid Chromatography

Purity assay and identity of omega-interferon recombinant in suspensionsystems by reverse phase high performance liquid chromatography(rp-HPLC).

The stability of omega-interferon was monitored in two different lots ofuntreated SAID (as received) and in treated SAID (removal of peroxides),when treatment was applied.

The studies are outlined below:

-   -   Study I: Stability in untreated SAI (lot #TD1030507) for 2 weeks    -   Study IIa: Treatment of SAI (lot #TD1030507) with neutral        alumina by heating and stability in this treated SAIB for 4        weeks    -   Study IIb: Treatment of SAIB (lot #TD1030507) with neutral        alumina in presence of ethanol and stability in this treated        SAID for 4 weeks    -   Study III: Stability in untreated SAID (lot #TD2032663) for 2        weeks    -   Study IV: Treatment of SAIB (lot #TD2032663) with basic alumina        by heating    -   Study V: Treatment of SAI (lot #TD2032663) with 10% aqueous        methionine solution by heating    -   Study VIa: Treatment of SAIB (lot #TD2032663) with 5% aqueous        solution of sodium metabisulfite and stability in treated SAID        for 8 weeks    -   Study VIb: Stability in untreated SAI (lot #TD2032663) for 8        weeks

TABLE 1 Details about stability studies of omega-interferon in SAIBStudy SAIB Particle Time # (Lot #) Treatment loading points Tests ITD1030507 Untreated  4% 0, 4, 7, SEC, 14 days RP- HPLC IIa TD1030507Treated with 10% 0, 2, SEC, neutral 4 weeks RP- alumina HPLC by heatingIIb TD1030507 Treated with 10% 0, 2, SEC, neutral 4 weeks RP- aluminaHPLC using ethanol III TD2032663 Untreated 10% 0, 1, SEC, 2 weeks RP-HPLC IV TD2032663 Treated with NA NA NA basic alumina by heating VTD2032663 Treated with NA NA NA 10% aqueous solution of methionine VIaTD2032663 Treated with 10% 0, 1, 2, 4, SEC, hexane and 8 weeks RP-sodium HPLC metabisulfite VIb TD2032663 Untreated 10% 0, 1, 2, 4, SEC, 8weeks RP- HPLC

Materials and Equipment

The following tables, Table 2 and Table 3, provide a list of materialsand equipment that can be utilized to perform the experiments described,below.

TABLE 2 List of materials Materials Spray dried omega-interferonparticles SAIB, Eastman Chemical Company Aluminum oxide (Powder)Ethanol, absolute, 200 proof, AAPER Aluminum oxide, basic, standardactivity I, 50-200 μm, Sorbent Technologies Aluminum oxide, basic, SuperI, 50-200 μm, Sorbent Technologies Methionine, USP, Ph Eur, JP

TABLE 3 List of equipment Equipment Branson Ultrasonic Cleaner Model2510 VAC Dry Box Mettler AT261 Delta Range Balance Mettler PJ3000Balance Sartorius Genius Electronic Analytical Balance Hot plate Oven(40° C.) Millipore filter, white hydrophilic, Durapore Disc, SLVP, 25mm, 5 μm PTFE membrane filter, 0.2 μm, Titan filtration systems

Example 1 Study I: Stability in Untreated SAID (Lot #TD1030507) for 2Weeks

TABLE 4 Stability of omega-interferon in untreated SAIB (lot #:1030507) - Study I Analysis by RP-HPLC (n = 3)** Initial (t = 0) (AR48452) 4 days 7 days 14 days (protein particles)*** AR48424 AR48562AR48450 Assay (%) NA 0.59* (0.02)  0.72 (0.00) 0.68 (0.00) % omega-IFN93.37 (0.40)  89.06 (0.46)  87.65 (0.06)  87.67 (0.26)  Purity %Oxidized  2.8 (0.71) 7.21 (0.88) 7.79 (1.09) 8.31 (0.10) % Deamidated 0.8 (0.02) 1.21 (0.00) 1.28 (0.01) 1.63 (0.03) % Unknown 3.03 (0.62)2.25 (0.66) 3.27 (0.79) 2.39 (0.38) Analysis by SEC (n = 3)** Initial(AR 48452) 4 days 7 days 14 days (protein particles)*** AR48424 AR48562AR48450 % Monomer 100.00 (0.00) 99.96 (0.01) 99.60 (0.02)  99.40 (0.00) % Dimer ND  0.04 (0.00) 0.38 (0.01) 0.58 (0.02) Unknown ND ND 0.01(0.00) 0.01 (0.01) *sampled by scraping container walls, so values mightnot be representative of the bulk ND = Not detected, **standarddeviation in parenthesis; ***protein particles − t = 0 for suspension

The preliminary stability study of omega interferon in untreated SAIB(lot #TD1030507, peroxide value—71.4 ppm) was over 2 weeks. The resultsindicated that up to 8.31% of omega-interferon was oxidized in twoweeks, which corresponds to an increase of 5.51% with respect toparticles (2.8% oxidation at t=0). See Table 4, FIG. 1. Furthermore, asmall increase occurred in the percentage of deamidated form (+0.83%) ofomega-interferon and the dimer (+0.58%). The high level of oxidation canbe attributed to the high peroxide content of SAIB.

Example 2

Study IIa and IIb: Stability of SAID (Lot #TD1030507) Treated withNeutral Alumina with Heating or Neutral Alumina in Presence of Ethanolfor 4 WeeksTreatment of SAIB with Neutral Alumina with Heating

SAIB was heated to 75° C. Alumina (15% w/w) was added to the heatedSAIB. The mixture was stirred for 40 minutes and filtered though a 5.0μm filter at 75° C. The treated SAID was then collected, sampled forperoxide testing, and used for preparation of suspension for stabilitytesting.

Treatment of SAIB with Neutral Alumina in Presence of Ethanol

SAID was mixed with 15% absolute ethanol to reduce the viscosity. Basicalumina (15% w/w) was added to the SAIB containing ethanol. Theresulting mixture was stirred for 1 hour and filtered though a 0.2 μmfilter. The filtered SAIB was placed overnight under vacuum at 60° C. toremove the ethanol. This treated SAIB was then collected, sampled forperoxide testing, and used for preparation of suspension for stabilitytesting.

TABLE 5 Stability of omega-interferon in alumina treated SAIB ((lot #:1030507) - Studies IIa and IIb SAIB treated with neutral alumina byheating - Study IIa Analysis by RP-HPLC (n = 3)** Initial (t = 0)Initial (t = 0) 2 weeks 1 month (protein particles) AR 48570 AR 48572 AR48565 Assay (%) NA 1.68 (0.01) 1.70 (0.00) 1.72 (0.01) % omega-IFNPurity 89.08 (0.56)  87.56 (0.47)  83.90 (0.15)  82.97 (0.50)  %Oxidized 1.72 (0.12) 3.45 (0.06) 6.85 (0.14) 7.39 (0.21) % Deamidated1.49 (0.01) 1.46 (0.03) 1.84 (0.03) 2.42 (0.05) % Unknown 7.70 0.45)7.52 (0.45) 7.41 (0.01) 7.22 (0.46) Analysis by SEC (n = 3)** Initial (t= 0) Initial (t = 0) 2 weeks 1 month (protein particles) AR 48570 AR48572 AR 48565 % Monomer 100.00 (0.00) 100.00 (0.00) 99.89 (0.01) 99.50(0.02) % Dimer trace 0.00  0.11 (0.01)  0.50 (0.02) Unknown 0.00 0.000.00 0.00 SAIB treated with neutral alumina using ethanol - Study IIbAnalysis by RP-HPLC (n = 3)** Initial (t = 0) Initial (t = 0) 2 weeks 1month (protein particles) AR 48570 AR 48572 AR 48565 Assay (%) NA 1.66(0.02) 1.7 (0.01) 1.70 (0.00) % omega-IFN Purity 89.08 (0.56)  88.12(0.49)  83.76 (0.09)  82.65 (0.19)  % Oxidized 1.72 (0.12) 3.08 (0.07)6.98 (0.12) 7.42 (0.10) % Deamidated 1.49 (0.01) 1.47 (0.01) 1.88 (0.02)2.45 (0.09) % Unknown 7.70 (0.45) 7.32 (0.48) 7.38 (0.02) 7.48 (0,05)Analysis by SEC (n = 3)** Initial (t = 0) Initial (t = 0) 2 weeks 1month (protein particles) AR 48570 AR 48572 AR 48565 % Monomer 100.00(0.00) 100.00 (0.00) 99.87 (0.01) 99.43 (0.02) % Dimer trace 0.00  0.13(0.01)  0.57 (0.02) Unknown 0.00 0.00 0.00 0.00 **standard deviation inparenthesis

The stability of omega-interferon in alumina treated SAIB was tested.After one month in the neutral alumina treated SAIB (Study IIa and IIb),oxidation of omega-interferon increased by about 5.7% for both IIa andIIb. This indicates that alumina treatment of SAID did not improve thestability of omega-interferon in SAIB. See Table 5. In addition, thisanalysis is also reflected in the high peroxide content of aluminatreated SAIB (66.3 and 62.9 ppm, respectively). Treatment with neutralalumina was not effective in decreasing peroxide content.

Example 3 Study M: Stability in Untreated SAI (Lot #TD2032663) for 2Weeks

TABLE 6 Stability of omega-interferon in untreated SAIB ((lot #:2032663) - Study III Analysis by RP-HPLC (n = 3)** Initial (t = 0) (AR48217) Initial (t = 0) 1 week 2 weeks (protein particles) AR 49640 AR49644 AR 49647 Assay (%) NA 1.69 (0.01) 1.70 (0.00) 1.68 (0.01) %omega-IFN Purity 88.98 (0.09)  88.21 (0.03)  84.95 (0.58)  83.71 (0.48) % Oxidized 1.63 (0.04) 3.20 (0.03) 6.39 (0.05) 7.21 (0.10) % Deamidated1.45 (0.01) 1.66 (0.01) 1.45 (0.40) 1.84 (0.03) % Unknown 7.94 (0.12)6.93 (0.04) 7.22 (0.45) 7.24 (0.45) Analysis by SEC (n = 3)** Initial (t= 0) (AR 48217) Initial (t = 0)* 1 week 2 weeks (protein particles) AR49640 AR 49644 AR 49647 % Monomer 99.93 (0.01) 99.83 (0.02) 99.75 (0.01)99.51 (0.01) % Dimer  0.07 (0.01)  0.17 (0.02)  0.25 (0.01)  0.49 (0.01)Unknown ND ND ND ND ND = Not detected *n = 6 **standard deviation inparenthesis

Stability of omega-interferon in untreated SAIB was again tested. Theresults of a two week stability study (Study III) of omega-interferon inSAIB (lot #TD 2032663) ae comparable to studies I and II. See Table 6,FIG. 4. The amount of oxidation was found to have increased by 5.58%,while deamidation increased by 0.39% and dimerization increased by0.42%.

Example 4

Study IV and V: Treatment of SAIB (Lot #TD2032663) with Basic Aluminawith Beating or with 10% Aqueous Methionine SolutionTreatment of SAI with Basic Alumina with Heating

SAIB was heated to 90° C. Basic alumina (15% w/w) was added to theheated SAIB. Two different grades of alumina were used—Basic Super I andBasic Standard Activity I. The resulting mixture was stirred for 40minutes. The mixture was then centrifuged at 4000 rpm while temperaturewas maintained at 75° C. After centrifugation, the supernatant wascollected and sampled for peroxide analysis.

Treatment of SAIB with 10% Aqueous Solution of Methionine

One part of SAIB was vigorously agitated with 4 parts of 10% aqueoussolution of methionine at 80° C. for 45 minutes using a magneticstirrer. (Evaporated water was replenished as necessary) Afterwards, themethionine solution was decanted. SAIB was then washed with 4 parts ofwater by agitating for 15 minutes at 70°-80° C. This washing step wascarried out three times. SAIB was placed overnight in vacuum oven at 70°C. to remove residual water, and, afterwards, was sampled for peroxideanalysis.

The peroxide content of SAI treated with basic alumina or with aqueousmethionine solution was determined to be 109.3 and 95.7 respectively(Study IV and V), indicating that these approaches were not successfulin the removal of peroxides. See FIG. 7.

Example 5

Study VIa and VIb: Stability of SAIB (Lot #TD20663) Treated with 5%Aqueous Solution of Sodium Metabisulfite or Untreated for 8 WeeksTreatment of SAIB with 5% Aqueous Solution of Sodium Metabisulfite inPresence of Hexane

SAIB was dissolved in two parts of hexane. The resulting solution wastreated with a 5% aqueous solution of sodium metabisulfite by vigorousshaking. The aqueous layer was removed and the SAID layer was washedwith water. The SAIB layer was dried with MgSO₄. Hexane was removed fromSAIB by evaporation under vacuum at 50° C. The treated SAIB was sampledfor peroxide analysis and used for preparation of suspension forstability testing.

TABLE 7 Stability of omega-interferon in untreated SAIB and treatedSAIB—Study VIa and VIb Stability of omega-IFN in Untreated SAIB (Lot: TD2032663) Analysis by RP-HPLC (n = 3)** Initial (t = 0) Protein particlesInitial (t = 0) 1 week 2 weeks 4 weeks 8 weeks AR 48219 AR 48445 AR48441AR 48440 AR 50132 AR 50161 Assay (%) 11.45 (0.24)  1.00 (0.01)  1.00(0.01) 1.00 (0.01) 0.94 (0.01) 0.94 (0.03) % omega-MN 88.91 (0.39) 87.29(0.25) 83.10 (0.08) 81.62 80.17 79.35 % Oxidized  1.90 (0.39)  3.38(0.19)  7.86 (0.14) 8.54 (0.07) 8.94 (0.08) 8.86 (0.06) % Deamidated 2.02 (0.01)  2.15 (0.03)  2.24 (0.09) 2.59 (0.15) 3.33 (0.04) 4.46(0.07) % Unknown  7.17 (0.44)  7.18 (0.47)  6.80 (0.02) 7.25 (0.36) 7.55(0.05) 7.33 (0.47) Analysis by SEC (n = 3)** Initial (t = 0) Proteinparticles Initial (t = 0) 1 week 2 weeks 4 weeks 8 weeks AR 48219 AR48445 AR48441 AR 48440 AR 50132 AR 50161 % Monomer 99.67 (0.01) 99.57(0.02) 99.16 (0.01) 98.93 99.15 97.18 % Dimer  0.25 (0.01)  0.31 (0.02) 0.72 (0.01) 1.01 (0.04) 0.47 (0.05) 2.53 (0.13) Unknown  0.08 (0.00) 0.12 (0.01)  0.12 (0.00) 0.06 (0.00) 0.38 (0.02) 0.30 (0.05) Note: Theomega content in the suspension was 1.00% and not 1.66% because theparticles contained 11.45% omega and the loading of particles insuspension was at 10% Stability of omega-IFN in Treated SAIB (Lot: TD2032663) Analysis by RP-HPLC (n = 3)** Initial (t = 0) Protein particlesInitial (t = 0) 1 week 2 weeks 4 weeks 8 weeks AR 48219 AR 48445 AR48441AR 48440 AR 50132 AR 50161 Assay (%) 11.45 (0.24)  1.17 (0.01)  1.15(0.00) 1.16 (0.00) 1.15 (0.00) 1.14 (0.01) % omega-IFN 88.91 (0.39)88.11 (0.35) 86.25 (0.41) 85.83 85.41 84.52 % Oxidized  1.90 (0.39) 2.69 (0.17)  3.26 (0.07) 3.46 (0.09) 3.56 (0.05) 4.16 (0.11) %Deamidated  2.02 (0.01)  2.26 (0.04)  2.81 (0.01) 2.94 (0.04) 3.21(0.06) 3.64 (0.06) % Unknown  7.17 (0.44)  6.97 (0.39)  7.68 (0.37) 7.77(0.38) 7.81 (0.45) 7.77 (0.55) Analysis by SEC (n = 3)** Initial (t = 0)Protein particles Initial (t = 0) 1 week 2 weeks 4 weeks 8 weeks AR48219 AR 48445 AR48441 AR 48440 AR 50132 AR 50161 % Monomer 99.67 (0.01)99.59 (0.02) 99.34 (0.02) 99.41 99.42 99.00 % Dimer  0.25 (0.01)  0.35(0.02)  0.53 (0.02) 0.54 (0.02) 0.29 (0.01) 0.94 (0.06) Unknown  0.08(0.00)  0.05 (0.00)  0.13 (0.01) 0.05 (0.01) 0.29 (0.01) 0.06 (0.01)Note: The omega content in the suspension was 1.17% and not 1.66%because the particles contained 11.45% omega and the loading ofparticles in suspension was at 10%. **standard deviation in parenthesis

The stability study (Study VIa and VIb, Table 7, FIGS. 5-7) conducted intreated (5% aqueous solution of sodium metabisulfite) and untreated SAIBshows that oxidation levels are reduced at 8 weeks, along with thereduction of peroxide levels—4.16% in treated SAIB versus 8.86% inuntreated SAID equivalent to a change of 2.26% and 6.96%, respectively,from t=0 values of the protein particles. (For all relative changesreported herein, the changes ae based on differences between thepercentage values, e.g., percent oxidation, at t_(n) and t=0 of theparticles as opposed to relative percent change from value at t=0).Deamidation increased by 2.44% and 1.62% in untreated and treated SAIB,respectively. Dimerization increased by 2.28% and 0.59% in untreated andtreated SAIB %, respectively. The quantities of unknown did not changesignificantly over time, which indicates that the extent of oxidation,deamidation and dimerization in treated SAIB (low peroxide value of 2.6ppm) was lower than in untreated material. This treatment decreased theperoxide content substantially.

TABLE 8 Peroxide content of SAIB SAIB Peroxide AR Study # (Lot #)Treatment value (ppm)* numbers I TD1030507 Untreated 71.4 48557 IIaTD1030507 Treated with neutral 66.3 48568 alumina by heating IIbTD1030507 Treated with neutral 62.9 48568 alumina using ethanol IIITD2032663 Untreated 115.9 48581 IV TD2032663 Treated with basic 109.348581 alumina by heating V TD2032663 Treated with 10% aqueous 95.7 48446solution of methionine VIa TD2032663 Treated with hexane and 2.6 49648sodium metabisulfite VIb TD2032663 Untreated 115.9** 48581 *oxidativeactivity equivalent to hydrogen peroxide (n = 1) **peroxide contentdetermined during Study III

As shown in FIG. 7, along with data provided in Table 8, treatment withan aqueous solution of sodium metabisulfite was effective insignificantly reducing peroxide levels from 115.9 ppm to 2.6 ppm—almost45 times, or 45 fold decrease. In comparison, treatment with neutralalumina, either with heat or with ethanol, resulting in only a nominalchange in peroxide levels—a 7% or 12% decrease, respectively. Inaddition, treatment with basic alumina with heat or 10% aqueousmethionine only resulted in nominal change in peroxide levels—a 6% or18% decrease, respectively.

FIG. 8 illustrates an osmotically pump-driven implantable device fordelivering an SAIB formulation acting as a drug delivery vehicle, activeagent within. Depicted in FIG. 8 is an osmotically pump-drivenimplantable device 10 shown comprising an impermeable reservoir 12. Thereservoir 12 is divided into two chambers by a piston 16. The firstchamber 18 is adapted to contain an SAIB formulation 19 containing anactive agent 20 and the second chamber 21 is adapted to contain afluid-imbibing agent. A back-diffusion regulating outlet 22 is insertedinto the open end of the first chamber 18 and a semipermeable membrane24 encloses the open end of the second chamber 21. The piston 16 isdriven towards the open end of the first chamber 18 by the osmoticpressure generated by the fluid-imbibing agent in the second chamber 21.The pressure created by the piston 16 can force the contents of thefirst chamber 18 out the opening, i.e., the SAIB formulation 19comprising active agents 20. The release rate of the active agent can begoverned by the osmotic pumping rate.

It is to be appreciated that certain features of the invention whichare, for clarity, described above in the context of separateembodiments, may also be provided in combination in a single embodiment.Conversely, various features of the invention that are, for brevity,described in the context of a single embodiment, may also be providedseparately or in any subcombination. Further, reference to values statedin ranges includes each and every value within that range, unlessclearly expressed otherwise.

The entire disclosure of each patent, patent application, andpublication cited or described in this document is incorporated hereinby reference.

1.-25. (canceled)
 26. A formulation comprising: a local anesthetic;sucrose acetate isobutyrate; and peroxide, wherein the peroxide ispresent in the formulation at a level ranging from 2.6 ppm to 20 ppm.27. The formulation of claim 26, wherein the peroxide is present in theformulation at a level ranging from 5 ppm to 20 ppm.
 28. The formulationof claim 26, wherein the peroxide is present in the formulation at alevel ranging from 10 ppm to 20 ppm.
 29. The formulation of claim 26,wherein the peroxide is present in the formulation at a level rangingfrom 2.6 ppm to 10 ppm.
 30. The formulation of claim 26, wherein theperoxide is present in the formulation at a level ranging from 5 ppm to10 ppm.
 31. The formulation of claim 26, further comprising apharmaceutically acceptable solvent.
 32. The formulation of claim 27,further comprising a pharmaceutically acceptable solvent.
 33. Theformulation of claim 28, further comprising a pharmaceuticallyacceptable solvent.
 34. The formulation of claim 29, further comprisinga pharmaceutically acceptable solvent.
 35. The formulation of claim 26,further comprising a solvent comprising hexane, ethyl acetate, ethanol,benzyl benzoate, N-methyl pyrrolidone, or isopropyl alcohol, or acombination thereof.
 36. A method of administering a local anesthetic,comprising administering the formulation of claim
 26. 37. A formulationcomprising: a local anesthetic; sucrose acetate isobutyrate; andperoxide, wherein the peroxide is present in the formulation at a levelranging from 2.6 ppm to 20 ppm, and wherein the formulation ispolymer-free.
 38. The formulation of claim 37, wherein the peroxide ispresent in the formulation at a level ranging from 5 ppm to 20 ppm. 39.The formulation of claim 37, wherein the peroxide is present in theformulation at a level ranging from 5 ppm to 20 ppm.
 40. The formulationof claim 37, wherein the peroxide is present in the formulation at alevel ranging from 2.6 ppm to 10 ppm.
 41. The formulation of claim 37,wherein the peroxide is present in the formulation at a level rangingfrom 5 ppm to 10 ppm.
 42. The formulation of claim 37, furthercomprising a pharmaceutically acceptable solvent.
 43. The formulation ofclaim 38, further comprising a pharmaceutically acceptable solvent. 44.The formulation of claim 39, further comprising a pharmaceuticallyacceptable solvent.
 45. A method of administering a local anesthetic,comprising administering the formulation of claim 37.